1. Field of the Invention
The present invention relates to a lens meter for measuring optical characteristics of a lens.
2. Description of Related Art
Conventionally, there is known a lens meter which projects a measurement light bundle onto a subject lens to be measured placed on a measurement optical axis, and photo-receives the measurement light bundle having passed through the subject lens by the use of a photo-sensor, and then obtains optical characteristics such as refractive power of the subject lens based on the photo-receiving results. In this kind of lens meter, a screen for alignment which is utilized to align a desired position or a desired region of the subject lens with the measurement optical axis is displayed on a display. For example, in the case of measuring a progressive power lens, a progressive power lens mark (a graphic image) representing the progressive power lens is fixedly displayed in the screen, and a target mark indicating a measurement position or a measurement region of the subject lens is concurrently displayed in the screen to be movable in response to movement of the subject lens relative to the measurement optical axis.
However, in the conventional lens meter, especially in the case of measuring the subject lens in frames or in other cases, confusion sometimes arises when grasping a correlation of a position and a movement direction of the subject lens relative to the measurement optical axis with a position and a movement direction of the target mark relative to the lens mark in the screen, and an inexperienced examiner sometimes takes trouble in alignment.